Vented reservoir for medical pump

ABSTRACT

The present invention concerns a medical pump comprising: a. A hard housing comprising a top ( 24 ) and bottom ( 1 ) hard shells, within which a rigid wall ( 3 ) and a movable membrane ( 2 ) create three distinct chambers; wherein i. said movable membrane tightly separates said second ( 29 ) and third ( 22 ) chambers ii. said first and third chambers have a watertight interface iii. said second chamber ( 29 ) is designed to contain a fluid iv. said first chamber ( 23 ) comprises a first venting mean ( 20 ) which is arranged to provide a fluidic communication between said first chamber ( 23 ) and the external environment; v. said third chamber ( 22 ) comprises a second venting mean which is arranged to provide a fluidic communication between said third chamber ( 22 ) and the external environment b. A pumping element ( 4 ) located in the first chamber ( 23 ) c. A least one pressure sensor which measure the pressure gradient between the first chamber ( 23 ) and the second chamber ( 29 ) d. A fluid pathway which permits: i. a first fluid connection ( 27 ) between said second chamber ( 29 ) and said pumping element ii. a second fluid connection ( 28 ) between said pumping element and a patient line ( 30 ).

FIELD OF INVENTION

The present invention is related to medical pumps, more specifically toreservoirs used with insulin pumps and means to prevent and detect anyover or under pressure in the reservoir.

STATE OF THE ART

Some insulin pumps, such as the one illustrated on FIG. 1, have a rigidchamber defined between a rigid wall (3) and bottom (1) hard shell. Apumping element (4) is fixed to the rigid wall (3). The chamber containsa reservoir which is made of a movable membrane (2) (e.g. soft pouch orflexible film), such as thermoformed and heat-soldered onto the rigidwall (3) (see for instance international patent application WO2007/113708). The bottom hard shell (1) protects the membrane (2)against external mechanical forces and ensures a water tightness of thesystem. The pump is vented using a hydrophobic filter in order toprevent a pressurization of the reservoir due to pressure or temperaturechanges. The risk of clogging with this filter is high and therefore apotential overdose becomes possible. Moreover such clogging cannot bedetected with the gauge pressure detector of the pump because thereference port of the detector is vented by the same filter than thereservoir itself. Therefore, said device described by WO 2007/113708can't detect a possible clogging of this vent which cause an over orunder delivery of the insulin to the patient.

The implementation of an additional anti-free-flow valve is a possibleway to overcome this problem. See WO 2008/029051. However, this may beexpensive for a disposable product and may not be totally fail safe.

GENERAL DESCRIPTION OF THE INVENTION

The present invention provides another advantageous solutions to preventan over or under delivery of fluid to the patient (for example: insulin)which is induced when the pressure gradient between the reservoir andthe external environment changes. Furthermore, the present invention mayadvantageously use with a method described in the application EP11172494.4.

To this effect, it relates to a medical pump comprising three distinctchambers. Said medical device is designed to form a hard housingcomprising a top and bottom hard shells. Said housing further comprisesa hard wall and a movable membrane which create said three distinctchambers. Said movable membrane tightly separates the second and thethird chambers. The first and third chambers have a watertightinterface. Said second chamber is designed to contain a fluid. Saidmovable membrane may be moved between said rigid wall and the bottomhard shell, in such a way that the fluid tight reservoir is formed bythe second chamber. Said first chamber comprises a first venting meanwhich is arranged to provide a fluidic communication between said firstchamber and the external environment. Said third chamber comprises asecond venting mean which is arranged to provide a fluidic communicationbetween said third chamber and the external environment. The devicefurther comprises a pumping element located in the first chamber, atleast one pressure sensor which measures the pressure gradient betweenthe first chamber and the third chamber. Said medical device comprises afluid pathway which permits a first fluid connection between said secondchamber and said pumping element and a second fluid connection betweensaid pumping element and a patient line.

With the present invention, the third chamber is completely vented bysaid second venting mean while maintaining the protection againstmechanical forces or ingress of solid foreign objects such as sharptips. In one of embodiment, said second venting mean is formed byseveral passages. The protection against water ingress is not insuredfor the third chamber, which is not necessary if said movable member isa tight membrane. While, the first chamber is vented by a vent which maybe hydrophobic and or oleophobic to protect the electronic part.

In one of embodiment, said movable membrane may transmit the pressure ofthe third chamber to said first fluid connection via the second chamberand the movable membrane. If, one or the both venting means get clogged,the pressure in the device and the pressure of the external environmentmay be different. The pressure gradient between inside device, inparticular in the third chamber, and the external environment may inducean over or under delivery of the fluid to the patient.

For this reason, the second venting mean comprises several passages(which reduce the clogging risk) and the device uses a method partiallydescribed in the application EP 11172494.4 for detecting if at least oneventing means is clogged.

The sensors may be localised in said chambers, in said fluid connectionsand/or outside.

The sensor may be a gauge pressure sensor localised between:

-   -   the third chamber and the first chamber, and/or    -   said first fluid connection and the first chamber, and/or    -   said second fluid connection and the first chamber, and/or    -   said third chamber and external environment, and/or    -   said first chamber and external environment.

The reference port of said gauge pressure sensors may be the externalenvironment, the first chamber or the third chamber.

In one of embodiment, the device comprises processing means for thesensor signal which may measure the pressure gradient between the thirdchamber and the first chamber or the external environment. And saidprocessing means detect a under or over pressure in said first chamberand/or said third chamber.

Said processing means can detect the clogging of said first venting meanand/or said second venting mean.

The medical pump comprises alarm means which alert the patient in caseof said first venting mean and/or said second venting mean are clogged.

LIST OF FIGURES

FIG. 1 shows the prior art of the medical device without the holes.

FIG. 2 illustrates an embodiment of the invention with several holes onone of hard shells

FIG. 3 represents the same embodiment as the one illustrated on FIG. 2but viewed from the other side.

FIG. 4 shows an exploded view of the complete system.

FIG. 5 shows the embodiment of the medical device with both ventingmeans are directly connected to the external environment.

FIG. 6 shows another embodiment of the medical device with the firstventing mean located between the first and the third chambers.

LIST OF ELEMENTS

1 Bottom hard shell

2 Movable membrane

3 Rigid wall

4 Pumping element

5 Holes

6 Baffles

7 Second venting mean

8 Upper face of the second chamber and/or third chamber

9 Lower face of the third chamber

10 Lateral face of the third chamber

11 Marks on the bottom shell

12 Filling port of the second chamber

13 Lateral slides

14 Grips

16 Battery

17 PCB (Printed Circuit Board)

18 Spring contacts

19 Battery contact

20 First venting mean

21 Lock

22 Third chamber

23 First chamber

24 Top hard shell

25 Upper face of the first chamber

26 Lower face of the first chamber

27 First fluid connection

28 Second fluid connection

29 Second chamber

30 Patient line

DETAILED DESCRIPTION OF THE INVENTION

The medical pump of the present invention comprises three distinctchambers (23, 29, 22). The second chamber (29) and the third chamber(22) is separated by a movable membrane (2) which may be moved between abottom hard shell (1) and the rigid wall (3) and comprises an upper face(8), a lower face (9) and a lateral face (10). Said bottom shell (1)contains several holes (5) which are forming the internal ends ofpassages (7) communicating between the third chamber and the externalenvironment.

The first chamber (23) is defined between the top hard shell (24) andthe rigid wall (3). Said first chamber (23) comprises an upper face(25), a lower face (26), a pumping element (4) and a first venting mean(20).

The third chamber and the first chamber are tightly separated by atleast said rigid wall (3) which is designed to form a watertightinterface.

In one of said embodiments, a hydrophobic surface treatment or coatingcan also be used on and/or around the holes (5) to limit the wateringress.

In one of said embodiments, said first chamber (23) comprises theelectronic elements.

In one of said embodiments, the lateral faces of said chambers areformed by the junction between part of the top and the bottom hard shellof the medical device.

The medical device comprises a first fluid connection (27) between saidsecond chamber (29) and said pumping element, and a second fluidconnection (28) between said pumping element and the patient line.

A sensor may measure a pressure gradient between the fluid and saidfirst chamber (23) and/or said third chamber (22) or between said bothchambers. Said sensor can be located upstream and/or downstream of thepumping element (4).

In a preferred embodiment, the sensor is a gauge pressure sensor. Thereference port of said gauge pressure sensor is connected to said firstchamber (23), allowing the detection of under or over pressure between:

-   -   said third and first chambers, and/or    -   the fluid and said first chamber, and/or    -   the fluid and said third chamber, and/or    -   the fluid and the patient line.

In case of one or both of said venting means are clogged, a positive ornegative pressure may be trapped in the third chamber (22) and/or in thefirst chamber (23). Therefore, the device further comprises alarm meanswhich can alert the patient if the first venting mean (20) of the firstchamber or/and the second venting mean (7) of said third chamber (22)are clogged.

Vent clogging case studies:

In a preferred embodiment, the change of pressure due to clogging can bemonitored using two gauge sensors located in the pumping element. Afirst gauge pressure sensor is located in the first fluid connection(27) which may measure the pressure of the third chamber which istransmitted to the second chamber (29) (and the first fluid connection(27)) via the movable membrane (2). A second gauge pressure sensor islocated in the second fluid connection (28) which may measure thepressure of the patient line. For both sensors, the reference port isthe first chamber (23).

1. Clogging of the second venting mean (7) only→potential over or underpressure in the third chamber (22) is transmitted to the fluid in thesecond chamber (29) via the membrane (2) and is detected via the firstsensor since the reference port (the first chamber (23)) of said sensoris not pressurized. The first sensor detects a pressure gradient betweenthe third chamber (22) and the first chamber (23) while the secondsensor doesn't detect any pressure gradient between the patient line andthe first chamber (23).

2. Clogging of the first venting mean (20) only→the first chamber (23)and therefore the reference ports of both sensors shall potentiallyexhibit over or under pressure with respect to external environment.Said over or under pressure will be detected by both sensors. Positive(respectively negative) pressure in said first chamber (23) leads to apressure signal equivalent to a negative (resp. positive) pressure inthe pumping chamber in normal conditions. Therefore, a clogging of saidfirst venting mean (20) is detected when the pressure in the firstchamber (23) becomes different from external environment pressure. Saiddifference of pressure inducing the same offset on both gauge pressuresensors with respect to a reference value obtained either by measuringthe pressure sensor signal before the priming of the pump or by usingcalibration data.

3. Clogging of all venting ports→the first and third chambers (23, 22)are potentially in over or under pressure with respect to the externalenvironment. Therefore, the first sensor can't detect any pressuregradient between the first and the second or third chambers. But, thepatient line pressure may be different. Therefore, the second sensor candetect a pressure gradient between the first chamber (23) and thepatient line.

FIG. 2 illustrates an embodiment of the invention where the bottom shell(1) is provided with passages (7) on its lateral face (10) of the thirdchamber. Each passage (7) is provided with a baffle (6) which definestwo opposite holes (5) oriented towards said lateral face (10), in adirection which is parallel with respect to the bottom face. In anotherembodiment, the holes are located within said lateral face (10) or saidlower face (9) of the third chamber.

In a preferred embodiment, said holes (5) are oriented in a directionwhich is forming an angle above 30° with the main direction of theirrespective passages (7).

FIG. 4 shows an exploded view of the complete system, including the sameembodiment as to the one illustrated on FIG. 2 and the top hard shell(24), the battery (16), a lock (21), the first venting mean (20), a PCB(17) and its spring contacts (18) to connect the pumping element (4)(not showed here) and finally the battery contact (19).

In the present invention the design of the bottom shell and moreparticularly the second venting mean (7) are driven by:

-   -   The capability to vent the membrane (2) for any foreseeable use        or probable misuse of the pump, including the presence of dirt        onto the pump, the wearing of the pump under clothes . . .    -   The protection against solid foreign objects

When second venting means (7), which is several passages like holes (5),are provided in the bottom shell (1) it is not possible to accidentallyclose all openings because of their specific locations. The compressionof the pump against a soft material on the top shell cannot typicallyobstruct these passages because of their lateral orientated location.The closure of the passages by lateral compression is also prevented bybaffles (6) that limit the access typically to fingers.

The passages (7) may have the shape of a slit or any other shape havingone dimension preferably lower than 1 mm.

The passages (7) may also be made into a recess and orientedperpendicularly to the normal of the lateral face (10) of the thirdchamber (22) in order to prevent the insertion of a straight and rigidtip, the minimum dimension of the opening being preferably no longerlimited to 1 mm in this configuration according to this recess.

The bottom shell (1) is preferably transparent; the patient should beable to see any large obstruction due to foods or any sticky stuff andeventually to change the disposable.

The bottom shell (1) and/or the rigid wall (3) and/or the membrane (2)are preferably made in plastic, and more generally in any materialhaving specific grades compatible with insulin. The use of the samematerial is desirable for thermowelding. The contact surfaces for gluingor thermowelding between the top and bottom shell should be large enoughto withstand reservoir overpressure up to 1 bar and drop test from aheight of 1 meter or more.

The membrane material has ideally a low elasticity and a lowpermeability. The membrane thickness is typically smaller than 100microns.

The surface of the membrane (2) is ideally larger than the surface ofthe lower face (9) of the third chamber (22) of the bottom shell toprevent any in-plane stress in the membrane and therefore any effect dueto the membrane elasticity.

The bottom shell (1) can advantageously include Moiré pattern. In caseof overfilling of the reservoir, when the membrane is directly incontact with the bottom shell, the reservoir pressure would bend thebottom shell and induce changes in the Moiré pattern, giving a visualfeedback of overfilling to the patient. The Moiré pattern covers partlythe bottom shell (1) surface in order to make possible the observationof bubbles into the reservoir.

The bottom shell may include any means to detect deformation due tostatic load or a pressurized reservoir (e.g. strain gauges, pressuresensors . . . ).

The passages (7) may be partly or completely covered by a removable andpermeable tape that ensures the venting of the reservoir. In case ofprojection of sticky stuff on the passages (7) the patient canadvantageously remove the tape instead of trying to clean up the deviceor simply changing it. The tape may be made of several sheets that canbe removed iteratively. Such air permeable tape may also cover the firstventing mean (20) of the first chamber (23).

The bottom shell (1) may include marks (11) that help the patient tofind the filling port (12) containing a septum.

The bottom shell (1) is ideally flat and has lateral slides (13) forpatch insertion (clipping) and grips (14) for patch removal(unclipping).

Fluid, e.g. water, can flow through the passages (7) and then in thespace between the bottom shell (1) and the membrane (2), the fluidtightness being only provided to the first chamber (23) of the pumpwhich, among other elements, includes the battery (16). The electronicand pump controller are in the first chamber which is water tight buthas to be vented in case a zinc-air battery needing oxygen and when agauge pressure sensors are used. The first chamber (23) is tightlyassembled using lock (21) or clips or any other means onto the upperface of the rigid wall (3), contacting electrically the pads of the pumpvia the spring contacts (18) of the Printed Circuit Board (PCB) (17).

The first chamber (23) uses the first venting mean (20) which istherefore preferably hydrophobic and/or oleophobic.

In another embodiment (FIG. 6), the first venting mean (20), which ishydrophobic, is located between the first and the third chambers.

In another embodiment, the device further comprises three distinctventing means. The first venting mean connects directly the firstchamber to the external environment, the second venting mean connectsdirectly the third chamber to the external environment and the thirdventing mean is located between the third and the first chamber. Thisembodiment insure a good venting in third and first chambers even if oneventing mean is clogged. Said third venting mean is preferablyhydrophobic and/or oleophobic.

1. Medical pump comprising: a. A hard housing comprising a top and bottom hard shells, within which a rigid wall and a movable membrane create three distinct chambers; wherein i. said movable membrane tightly separates said second and third chambers ii. said first and third chambers have a watertight interface iii. said second chamber is designed to contain a fluid iv. said first chamber comprises a first venting mean which is arranged to provide a fluidic communication between said first chamber and the external environment; v. said third chamber comprises a second venting mean which is arranged to provide a fluidic communication between said third chamber and the external environment b. A pumping element located in the first chamber c. A least one pressure sensor which measure the pressure gradient between the first chamber and the second chamber. d. A fluid pathway which permits: i. a first fluid connection between said second chamber and said pumping element ii. a second fluid connection between said pumping element and a patient line.
 2. Medical pump according to claim 1, wherein said second venting mean is provided by several passages.
 3. Medical pump according to claim 1 wherein said movable membrane transmits the pressure of the third chamber to said first fluid connection.
 4. Medical pump according to claim 1, wherein said pressure sensor may be located in the first chamber, in the third chamber, in the pumping element, in the first fluid connection and/or in the second fluid connection.
 5. Medical pump according to claim 1, wherein said pressure sensor is gauge pressure sensor which measures the pressure gradient between said first chamber and said second chamber and wherein the reference port of said gauge pressure sensor may be the external environment, the first chamber or the third chamber.
 6. Medical pump according to claim 1, further comprising processing means for the sensor signal wherein said processing means detect an under or over pressure in said first chamber and/or said third chamber.
 7. Medical pump according to claim 1 wherein said first venting mean of said first chamber is a hydrophobic and/or oleophobic vent.
 8. Medical pump according to claim 7 wherein said first venting mean of said first chamber is located between the first and the third chambers.
 9. Medical pump according to claim 1 comprising a third venting mean which is a hydrophobic vent and which is located between the first and the third chambers.
 10. Medical pump according to claim 3 wherein said passages are oriented towards the lateral face of the third chamber.
 11. Medical pump according to claim 3 wherein said passages are located within the lateral face of the third chamber.
 12. Medical pump according to claim 3 wherein said passages are located within the lower face of the third chamber.
 13. Medical pump according to claim 1 wherein said passages include holes which are oriented in a direction forming an angle above 30° with the main direction of their respective passages.
 14. Medical pump according to claim 1, wherein the internal end of said passages is provided with a baffle.
 15. Medical pump according to claim 1, comprising alarm means to alert the patient in case of said first venting mean and/or said second venting mean are clogged.
 16. Medical pump according to claim 1 wherein the hard shell of the third chamber is transparent.
 17. Medical pump according to claim 1 wherein the hard shell of the third chamber includes Moiré pattern.
 18. Medical pump according to claim 1 wherein a hydrophobic surface treatment or coating is added around the passages.
 19. Medical pump according to claim 1 wherein the passages are protected by a removable and permeable tape.
 20. Method for preventing an over or under delivery of the fluid contained in the medical device as defined in claim 1, wherein the method comprises the measurement of the pressure in said first and second chambers and the comparison of these pressures.
 21. Method according to claim 20, further comprising the measurement of the gradient pressure between the first fluid connection and the first chamber—by a first gauge pressure sensor—and/or between the second fluid connection and the first chamber—by a second gauge pressure sensor wherein the reference port of both sensors is the first chamber.
 22. Method according to claim 21, wherein a clogging of said second venting mean is detected when the first gauge pressure sensor measures a pressure gradient while the second gauge pressure sensor doesn't measure a pressure gradient.
 23. Method according to claim 21, wherein a clogging of a clogging of said first venting mean is detected when the pressure in the first chamber becomes different from external environment pressure and when said difference of pressure inducing the same offset on both gauge pressure sensors with respect to a reference value obtained either by measuring the pressure sensor signal before the priming of the pump or by using calibration data.
 24. Method according to claim 21, wherein a clogging of all venting means is detected when the second gauge pressure sensor measures a pressure gradient while the first gauge pressure sensor doesn't measure any pressure gradient.
 25. Method according to claim 1, said method comprising the triggering of an alarm when the pressure in the first and/or third chamber becomes different from external environment pressure or from one of said chambers. 